Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
  Case Tag  
Price  
Sales  
Tax %  
Raw Total  
Incl. Sales Tax  
Rounded  
to Penny  
Rounded  
to Nickel  
Rounded  
to Dime  
  Purchase #1 $84.95   11.848%   $95.0149   $95.01   $95.00   $95.00  
  Purchase #2 $245.79   5.803%   $260.0532   $260.05   $260.05   $260.10  
  Purchase #3 $187.84   10.506%   $207.5745   $207.57   $207.55   $207.60  
  Purchase #4 $33.42   6.536%   $35.6043   $35.60   $35.60   $35.60  
  Purchase #5 $152.65   6.768%   $162.9814   $162.98   $163.00   $163.00  
  Purchase #6 $12.58   13.137%   $14.2326   $14.23   $14.25   $14.20  
  Purchase #7 $165.61   10.771%   $183.4479   $183.45   $183.45   $183.40  
  7 purchase totals = $882.84       $958.9088   $958.89   $958.90   $958.90